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Thursday, July 26, 2012

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Time travel

Einstein showed that time runs at different speeds in different places – and is just another dimension. Ever since, some scientists have wondered whether we could travel through time to the past or the future.

Einstein said you cannot move through time because you would have to travel faster than light. If you travelled as fast as light, time would stop and you would not exist.

A famous argument against time travel is about killing your grandparents. What if you travelled back in time before your parents were born and killed your grandparents? Than neither your parents nor you could have been born. So who killed your grandparents?

In the 1930s American mathematic Kurt Godel found time travel might be possible by bending space time.

Scientists have come up with all kinds of weird ideas for bending space-time, including amazing gravity machines. The most powerful benders of space-time are black holes in space

Stephen Hawking said you cannot use black hole for time travel because everything that goes into a black hole shrinks to a singularity. Others say you might dodge the singularity and emerge safely somewhere else in the universe through a reverse black hole called white hole.

US astronomer Carl Sagan thought that small balck hole –white hole tunnels might exist without a singularity. There might be tunnels such as these linking different part or the universe, like a wormhole in an apple.

The mathematics says that a wormhole would snap shut as soon as you stepped into it. However, it might be possible to hold it open with an anti-gravity machine based on a quantum effect called the Casimir effect.

Stephen Hawking says wormholes are so unstable that they would break up before you could use them to time travel. Martin Visser says you might use them for faster than light (FTL) travel, but not for time travel.

~ if wormhole exist, they are thought to very-very tiny smaller than an atom. So how could they be used for time travel? Some scientist think you may be able to use an incredibly powerful electric field to enlarge them and hold them open long enough to make a tunnel through space-time.

source: ~ 800 things you should know, Miles Kelly ~ 1000 thing you should know about science, time travel m/s 300